Chemical fuel cells utilize renewable resources and provide an alternative to burning fossil fuels to generate power. Fuel cells utilize the oxidation/reduction potentials of chemical reactions to produce electrical current.
For example, methanol is a known example of a fuel source used in chemical fuel cells. In a methanol driven fuel cell, methanol and water can be circulated past an anode that is separated from a cathode by a membrane that is selectively permeable to protons. The following chemical reaction takes place at the anode. EQU Anode: CH.sub.3 OH+H.sub.2 O .fwdarw.CO.sub.2 +6H.sup.+ +6e.sup.-
The protons generated at the anode pass through the membrane to the cathode side of the fuel cell. The electrons generated at the anode travel to the cathode side of the fuel cell by passing through an external load that connects the anode and cathode. Air or an alternative oxygen source is present at the cathode where the electro-reduction of oxygen occurs resulting in the following chemical reaction. EQU Cathode: 1.50.sub.2 +6H.sup.+ +6e.sup.- .fwdarw.3H.sub.2 O
One of the key aspects of a chemical fuel cell is the membrane-electrode assembly (MEA). The MEA typically includes a selectively permeable polymer electrolyte membrane bonded between two electrodes, e.g., an anode electrode and a cathode electrode. The materials chosen for constructing the membrane should allow protons to pass through the membrane and prevent the fuel sources from passing through the membrane.
When the fuel, e.g., methanol, permeates the membrane and combines with oxygen on the cathode side of the fuel cell, the overall operating potential of the fuel cells is diminished. This phenomenon is termed fuel crossover. The rate of crossover is a parasitic reaction that is proportional to the permeability of the fuel through the membrane and increases with increasing fuel concentration and temperature. Thus, choosing the appropriate membrane material can increase the overall fuel cell performance.
One currently preferred resin of choice for fabricating MEAs has been NAFION (TM), which is a co-polymer of a tetrafluoroethylene and perfluorpolyether sulfonic acid made by DuPont De Nemours. NAFION (TM) membranes are chemically stable, strong and reasonably conductive. There are at least two drawbacks associated with NAFION (TM). NAFION (TM) is extremely expensive. Further, NAFION (TM) suffers from fuel crossover. Accordingly, there exists a need for improved and cost-effective fuel cell electrolyte membranes.